The ability to make advantageous decisions under conditions of risk is negatively related to health-risk behaviors such as delinquency, alcohol and drug use, and risky sexual behaviors. Although prior researchers have emphasized the importance of individual differences in and the developmental course of advantageous decision making, much of their research has relied on complex tasks designed to parallel real-life risky decision making. However, the complexity of these tasks has made it challenging to deconstruct the effects of outcome valence, probability level, and outcome magnitude on decision making and to examine the event-related potential (ERP) correlates of decision making. Thus, the underlying processes of decision making are not well understood. In the proposed study, we will modify an existing decision-making task, the Cups Task, for use with ERP techniques. The Cups Task assesses the ability to make advantageous decisions within the context of pure gains and losses. Each trial consists of a riskless choice that has a certain gain or loss and an uncertain, or risky, choice that has the potential to increase or decrease the gain or loss. A factorial manipulation of the probability level and outcome magnitude for the risky choices yields trials that are risk advantageous, risk equivalent, or risk disadvantageous based on the relative expected value of the certain and risky choices. Behavioral performance (e.g., proportion of risk-disadvantageous choices) and electrophysiological performance (e.g., amplitude of identified ERP components) on the modified task will be assessed in 150 participants (75 females) equally distributed across three age groups: late childhood (ages 10-11), early adolescence (ages 13-14), and late adolescence (ages 16-17). The modified task will be validated by examining the associations between behavioral and electrophysiological performance on this task and related measures such as behavioral indices of risky decision making. Additionally, the resulting dataset will provide an opportunity to examine the development of the underlying processes of decision making from late childhood to late adolescence. It is believed that research examining the processes underlying decision making will lead to the development of more precise explanatory models linking specific decision-making processes to later health-risk behaviors. Thus, this vein of research has the potential to aid in the early identification of children and adolescents at risk for later health-risk behaviors and to identify potential targets or preventive intervention services for these at-risk youth.